Method of lining pipe



March 5, 1963 w. PoLLocK ETAL 3,080,269

METHOD oF LINING PIPE Filed May 2l. 1959 2 Sheets-Sheet 1 L W/AW A k l/f (ZJ. a/szw ATTORNEY March 5, 1963 w. PoLLocK l-:TAL 3,080,269

METHOD oF LINING PIPE Filed May 21. 1959 2 Sheets-Sheet 2 V//AV///M\ /43/ll/ l//l//l//l//l GEF/4R0 H. PR01/007' BY//VL TER POL LOCK Maw A TIoBNEY' States This invention relates to a method of lining pipe withplastic material. The term plastic material is intended to refer tomaterial which may, `for example, be a thermoplastic or thermosettingplastic, rubber or the like.

In prior methods of lining pipe with plastic material, yit has beencustomary to introduce air under pressure into the lining tube. Solidend plugs have been employed to maintain end seals in the lining tube.Accordingly, when the lining tube expands during the manufacturingprocess, leakage of the compressed 'air from the lining tube may occur.Also, the use of high pressure inside the lining tube may cause thelining to expand too quickly to allow air to escape between the liningtube rand the pipe, resulting in non-uniforrnities or blow-outs in thelining.

It is an object of the present invention, therefore, to avoid one ormore of the above mentioned disadvantages and limitations of priormethods of lining pipe.

It is another object of the invention to provide a new and improvedmethod of lining pipe with plastic material which is not subject toblow-outs" of the lining during manufacture.

It is another object of the invention to provide a new and improvedmethod of lining pipe with thermoplastic material which is not subjectto leakage of `air pressure from the interior of the lining tube duringmanufacture.

l-n .accordance with a particular form of the invention, ya method oflining pipe with thermoplastic material comprises applying an adhesiveto at least one of a pipe to be lined and a lining tube of thermoplasticmaterial which is longer than the pipe. The method also comprisesinserting the lining tube in the pipe with the tube projecting from eachend of the pipe, placing an inflatable end sealer inside each end of thelining tube and placing an outer coupling member supporting the sealingmember and of approximately the same diameter as the pipe outside eachend `of the lining tube, clamping the outer coupling members to the pipewhile maintaining a vent between each end of the pipe :and the ends` ofthe coupling members to allow air to escape between the pipe and thelining tube, intlating the end sealing members to expand them againstthe lining tube, and heating the pipe, lining tube, and end sealingmembers to expand the lining tube in the regions of the end sealingmembers into intimate contact with the pipe and to expand the endsealing members with the li-ning tube against the outer coupling membersto maintain the seal.

For a better understanding of the present invention, together with otherand further objects thereof, reference is made to the followingdescription taken in connection with the accompanying drawing, and itsscope will be pointed out in the appended claims.

Referring to the drawings:

FIG. l is -a fragmentary view, in section, of a pipe to be lined, with alining tube and end sealer installed in accordance with the method ofthe present invention;

FIG. 2 is a fragmentary View, in section, of the FIG. 1 pipe, liningtube, and end sealer after the lining has been expanded in accordancewith the method of the present invention; and

FIG. 3 is a fragmentary view, in section, of a pipe, liuing tube, andend sealer after the lining has been expanded in accordance with themethod of the present invention.

Referring now more particularly to FIG. 1 of the drawatent O 3,080,269Patented Mar. 5, 1963 ICC ings, the interior surface of a metal pipe 10is cleaned in an appropriate manner, -for example, by sand blasting orby means of a solvent. A suitable adhesive is applied to interior of thepipe 10 and to exterior of a lining tube 11, which may, for example, beof thermoplastic material, such as a vinyl-type resin, or of lathermosetting material, such as rub-ber in an uncured or semi-curedstage. The lining tube 11 then is inserted in the pipe 10 as representedin FIG. l, with an end portion 12 projecting from each end of the pipe10.

An inflatable end sealer 13 comprising an inflatable member 14 and an-outer coupling member 15 is placed at each end of the lining tube 11with the inllatable member 14 inside the lining tube and the outercoupling member outside the lining tube. The diameter of the outercoupling member 15 preferably is approximately the same `as the diameterof the pipe 10. The end 15a of the outer coupling member 15 preferablyis sp-aced from the end of the pipe 10 to form a gap or vent to allowair to escape between the pipe 10 and the lining tube 11. To this end,-a clamp 16 for attaching the end sealer to the pipe 11il has anaperture 17 therein aligned with the gap between the outer couplingmember 15 and the pipe lil,

The end sealer .13 includes a pair of metal end caps or plugs 18, 19,and clamp rings for closing the inflatable member 14. Alternatively, theinatable member of the end sealer might simply be an inflatable bag.There is inserted in the end cap 19 a liller tube 20 having anassociated valve 21 for `controlling the inllation of the end sealer.

The end sealer 13 and the end sealer at the other end of the pipe 10(not shown) are then inflated to a pressure of, for example, 30 to 6()pounds to expand the end sealers against the lining tube. The .assemblyof pipe 10, lining tube 11, and end Sealers is then heated in an ovento, for example, 200 132-300o F. to expand the lining tube against thepipe and to expand the end seal'ers with the lining tube to maintain theseal, as represented in FIG. 2. While the yassembly is being heated andthe lining tube is expanding, air escapes between the lining tube 11 andthe metal pipe 10 through the gap between the end of the pipe 10 and theend 15a of the outer coupling member of the end sealer and through theaperture 17 in the clamp 16. Because the gap between the end of the pipe10 and the end 15a of the outer coupling member is small, the chances ofblowing out at the gap are minimized. Also, because the end `sealerutilizes an inflatable member which expands with the lining tube 11,there is a pressure build-up within the lining tube 11 to causeextension of the tube with minimum air leakage during the heating cycle.Thereafter, the assembly is cooled and the end sealers are removed. Theend of the thermoplastic lining tube extending beyond the pipe 10 maythen be cut to -be ilush with the pipe.

lf desired, as represented in FIG. 3 a tube 30 having a valve 31 mayextend through the end sealer to apply additional air pressure, forexample, 30 pounds per square inch, inside the lining tube 11 in theevent that the lining tube is of a relatively rigid material.

While there has been described what is at present considered to be thepreferred method in accordance with this invention, it will -be obviousto those skilled in the art that various changes and modifications maybe made therein, without departing from the invention, and it is,therefore, yaimed to cover all such changes and modifications as fallwithin the true spirit and scope of the invention.

Having thus described our invention, what we claim and desire to protectby Letters Patent is:

1. A method of lining pipe with thermoplastic material comprising:applying an adhesive to at least one of la pipe to be lined and Ialining tube of thermoplastic material which is longer than the pipe,inserting the lining tube in the pipe with the tube projecting from eachend .of the pipe, placing yan inatable end sealing member inside eachend of the lining tube and placing an `outer coupling member supportingthesealingomember and of'approximately .the same `diameter as the pipeoutsidereachendof the liningtube, clamping the Vouter coupling membersto the pipe while. maintaining a vent between each end of the pipe andthe ends of the coupling members to allow air to escape between the pipeand the' lining tube, inating the end sealing members to expandthemagainst the lining tube, and heating the pipe, lining tube and endsealing members to expand the lining tube in the regions of the endsealing members into intim-ate contact with the pipe and to expand theend `sealing members with the lining tube against Ithe outer couplingmembers to maintain the seal.

2. A method of liningpipe with thermoplastic materialcomprisingz'cleaning the inner surface of a metal pipe'to be lined,applying an adhesive to the inner surface of the pipe and to the outersur'faceiofalining tube of thermoplastic material w-hich is longer thanthe pipe, inserting the lining 'tube in the pipe with the tubeprojecting from each end of the pipe, placing an inflatable endsealingmem-ber inside each end of thelining tube and an outer coupling membersupporting the sealing member and of approximately the same diameter asthe pipe outside each end of the lining tube, clamping the outercoupling members to the pipe while maintaining a vent between each endof the pipe and the en-d of the coupling member to 'allow air to escapebetween the pipe and the lining tube, inlating the end sealing membersto expand them against the lining tube, and heating the pipe, liningtube and end sealing members to expand the lining tube in the regions ofthe end sealing members into intimate contact with the pipe and toexpand the sealing members with the lining tube against the outercoupling members to maintain the seal, and thereafter cooling the pipe,lining tube and end sealing members while assembled as a unit and withthe endfsealing members still inflated.

References Cited in the le of this patent UNITED STATES PATENTS2,312,993 Stephens Mar. 2, 1943 2,440,725 Munger May 4, 1948 2,608,501Kimble Aug. 26, 1952 2,779,996 Tanis Feb. 5, 1957 FOREIGN PATENTS374,842 Great Britain June 2, 1932 453,123 Great Britain Sept. 1,1936

1. A METHOD OF LINING PIPE WITH THERMOPLASTIC MATERIAL COMPRISING:APPLYING AN ADHESIVE TO AT LEAST ONE OF A PIPE TO BE LINED AND A LININGTUBE OF THERMOPLASTIC MATERIAL WHICH IS LONGER THAN THE PIPE, INSERTINGTHE LINING TUBE IN THE PIPE WITH THE TUBE PROJECTING FROM EACH END OFTHE WHICH IS LONGER THAN THE PIPE, INSERTING THE LINING TUBE IN END OFTHE LINING TUBE AND PLACING AN OUTER COUPLING MEMBER SUPPORTING THESEALING MEMBER AND OF APPROXIMATELY THE SAME DIAMETER AS THE PIPEOUTSIDE EACH END OF THE LINING TUBE, CLAMPING THE OUTER COUPLING MEMBERSTO THE PIPE